1. Technical Field
The present invention relates generally to Pulse Code Modulated/Time Division Multiplexed data communications apparatus and more particularly to an improved means for accomplishing high frequency demultiplexing.
2. Discussion of the Prior Art
FIG. 1 represents individual electronic data sources Ia, Ib, Ic, . . . timed by local oscillators (CLKa), (CLKb), (CLKc) and transmitting Pulse Code Modulated (PCM) data signals at input rates RATEa, RATEb, RATEc, via Input Tributaries (ITa, ITb, ITc) to inputs of a conventional Time Division Multiplexer (TDM MUX). TDM MUX, driven by its transmitter-oscillator Master CloCK (MCLK), samples the tributaries in some selected order at a rate faster than the total allowed input rate and, as higher frequency-translated data bit signals, multiplexes then into time-slots of a PCM/TDM signal stream. This stream is then received and de-multiplexed by PCM/TDM demultiplexer TDM DEMUX, which produces individual output data streams on output tributaries OTa, OTb, and OTc, to output devices Oa, Ob, and Oc. Clock recovery unit CLKR derives the Bit CLocK signal (BCLK) from the PCM/TDM signal stream for use by the TDM DEMUX. After clock recovery has been performed, the demultiplexing process involves the additional steps of frame alignment, dejustification, and decommutation.